Where’s the Beach? Under the Seaweed.

Digging out at St. James's Club, Antigua, Aug. 23

AN invasion of seaweed that is extraordinary in volume and geographic scope has been besieging the eastern Caribbean since June, sending resorts and government agencies from Anguilla in the north to Tobago in the south scrambling to rid beaches of the smelly, brown, bug-attracting algae before the impending high season.

In Antigua, the $600-a-night St. James’s Club & Villas was forced to close for the month of September while it removed 10,000 tons of seaweed from its beaches. The weed, a floating species of algae known as Sargassum that inhabits the Sargasso Sea, had completely filled the bay on which the hotel sits and created piles as high as five feet tall on the usually pristine shore. In St. Maarten, swimmers were warned away from some beaches because of fears that they could get tangled in the seaweed and drown. In Barbados, the government installed an oil-containment boom across the mouth of a river on its northeast shore to keep the weed at bay. In Tobago, where for several months workers have been carting the stuff off beaches regularly and trucking it to the dump, the government has been encouraging farmers to use it as fertilizer.

“This is completely unprecedented,” said David Freestone, executive director of the Sargasso Sea Alliance in Washington, which has been fielding reports of unusual quantities of the seaweed washing ashore in places as far-flung as Sierra Leone in West Africa. While small amounts of Sargassum are normally found in the Caribbean from May to September when regional currents and winds transport the floating algae to the islands, such large accumulations across so many regions, he said, has “never happened in living memory.”

Theories as to why range from shifts in ocean currents to climate change to the gulf oil spill. But at least for now, “it’s a mystery,” Mr. Freestone said.

Resorts and tourism officials fear that the weed could linger into high season, which starts in November, but anecdotal reports suggest that the worst may be over. Ramon Roach, a water-quality analyst for the Barbados Coastal Zone Management Unit who has been part of the effort to clear the weed, said that in the last week and a half, “we haven’t seen any additional seaweed coming from the sea.”

And according to Jerald Ault, professor of marine biology and fisheries at the University of Miami, cooler fall weather traditionally slows algae’s growth, changes ocean circulation patterns, water temperature and nutrient systems. These shifts, he said, “typically keep the weed at sea.”

Though not a threat to human health, the seaweed, which attracts flies and smells like rotten eggs as it decomposes, is a nuisance at best and a repellent at worst. If it is thick in the water it can harbor plastic and other garbage, making swimming hazardous. Concerns that swimmers could become ensnared by it led the Nature Foundation St. Maarten to issue a warning in August advising swimmers to steer clear of Guana Bay Beach and Gibbs Bay, which were inundated with Sargassum until a few weeks ago when storms swept much of the algae to sea.

While there is still “quite a bit of weed washing ashore,” said Tadzio Bervoets, director of the Nature Foundation, “the situation has gotten better.” But for islands that depend on tourism, that’s not enough. “Tourists don’t want to see it or smell it; it can’t be there,” said Eli Fuller, owner of Adventure Antigua, a tour company with an environmental bent, who has been writing about the seaweed influx at antiguaisland.blogspot.com. While many of Antigua’s beaches are free and clear of the seaweed, he said, if a visitor “left their hotel and went for a drive, say, to Half Moon Bay,” normally a beautiful eastern beach, “they would find lots of weed on it.”

Accounts of the severity of the situation vary depending on whom you ask, with hotel and tourism officials often painting rosier pictures. Inès Bouchaut-Choisy, a director of the Saint-Barthélemy Tourism Committee, described the situation on St. Barts’s 22 beaches as “ribbons of algae” that are “decorating the sand” on only three beaches: St. Jean, Lorient and Public.

Deborah Brosnan, a marine biologist who lives there and has been chronicling the Sargassum phenomenon on BrosnanCenter.com, said though amounts vary, “it’s on all the beaches.”

On nearby Anguilla, “it has been coming in droves,” said A. Nat Hodge, editor and publisher of The Anguillian, a local newspaper, saying that there was a surge at the beginning of the month. Anguilla officials said that removal efforts have been under way for weeks. “In some cases private contractors have been commissioned to remove the weed,” said Candis Niles, director of tourism for the Anguilla Tourist Board, “but in most cases, business operators on the beach as well as community volunteers are taking the initiative to clean up the seaweed on a regular basis so that the appearance of the beaches is maintained.”

One consolation is that it is currently the rainy season in the Caribbean when fewer tourists visit and some elite resorts on islands like St. Barts are closed anyway. Nevertheless, islands are worried that if word of messy beaches spreads, tourists may decide to go elsewhere — even if the problem is resolved soon.

For anyone headed to the Caribbean before then, the probability of finding a seaweed-covered beach is greater in some places than others.

For the most part island governments and marine experts say, the bulk of the seaweed is ending up on the eastern side of the islands, where beaches tend to be rockier with fewer resorts.

On French St. Martin, northern beaches like the popular Orient Bay and Le Galion as well as the east coast beaches have been the most affected, said Jadira Veen, president of the Sint Maarten PRIDE foundation, a nonprofit environmental awareness group. On the Dutch side, Guana Bay Beach has been out of commission for months because of the seaweed, she said. But hotel beaches are likely to be assiduously tended, which can make a difference. Dawn Beach, for example, which is also on the east coast and has been faced with large amounts of seaweed, is mostly clear of it because several hotels have been working hard to keep the beach attractive for tourists, Ms. Veen said.

Meanwhile, Mullet Bay beach, Cupecoy beach and others on the western side of the island “are still pristine white sandy beaches as one expects in the Caribbean,” she said.

The seaweed invasion comes at time when Caribbean tourism has not yet not fully recovered from the effects of the recession. “Business has not been exactly booming,” said Rob Barrett, chairman of Elite Island Resorts, which includes the St. James’s Club, the hotel which was forced to close so that it could clear thousands of tons of seaweed from its beach. “We are still in a recovery period and then this hits,” he said. “It was just like an onslaught. If you were standing behind it, you wouldn’t see the ocean.” Mr. Barrett said that it took three backhoes and five 10-ton dump trucks hauling seaweed “12 hours a day, 7 days a week for 3 weeks” to clear the beach, which he said is now pristine. The effort, combined with the loss of guests during the closure, cost the company about $1 million.

There could be environmental fallout as well. Seaweed plays an important role in the Caribbean ecosystem, and such large quantities can have positive and negative effects. Sargassum can help bulk up eroding beaches, for example. But large deposits can also make it difficult for tiny sea turtle hatchlings to find their way to the ocean. “It’s an intrusion on tourism,” Mr. Ault said. “But the reality is it serves as fertilizer on beaches and it may turn out to be extremely positive for fishery resources,” because the seaweed becomes a refuge and a food source for young fish and other sea creatures.

The big unknown is what happens next year. “The question of whether it was an exception to the rule or representing some sort of regime shift in the way ocean currents are operating is a pretty major question,” said Jeff Ardron, director of the High Seas Program for the Marine Conservation Institute in Washington, who has been tracking the issue. A repeat, he said, could “strongly indicate that something serious is afoot.”